In many spinal fixation procedures, a spinal fixation rod is connected to implants attached to two or more vertebrae. When pedicle screws are used, the spinal fixation rod can be inserted into a rod receiving component associated with each pedicle screw. Minimally invasive procedures can make rod insertion difficult, because the surgeon only makes small incisions to insert each pedicle screw. Once the pedicle screws are attached to the vertebrae, the rod receiving components are not visible beneath the incisions. Inserting a spinal fixation rod through a first pedicle screw and navigating the rod beneath tissue into a second pedicle screw is very challenging. Minimally invasive procedures, such as percutaneous procedures, are disfavored in multi-level cases because of the difficulty in guiding the spinal fixation rod through small incisions and beneath tissue. This is particularly the case where the pedicle screws have different heights and/or medial lateral positions, forming a non-linear path to which the rod must conform.
In cases where the pedicle screws are not aligned, some surgeons choose a manual insertion approach in which the surgeon guides the rod and uses tactile feedback, with or without x-ray imaging, to check the position of the rod relative to the implants. This process is extremely difficult, and does not provide the surgeon with any way to accurately determine the proper length and curvature for the rod. Other surgeons use extensions connected to the implants to assist in inserting the rod. These mechanical approaches typically do not work in multi-level cases where the heights of the implants and/or medial-lateral positions of the implants are substantially offset from one another.